Method for balancing over-voltage and under-voltage of battery cell, battery management system and vehicle

Abstract

The invention provides a method for balancing over-voltage and under-voltage of a battery cell, a battery management system and a vehicle, and belongs to the technical field of battery cell balancing. The method is applied to a battery management unit in a battery management system, and comprises the following steps: receiving an equalization instruction issued by an upper computer, and collecting the voltage of each single cell in each battery pack in real time; generating a voltage detection signal corresponding to the to-be-balanced single cell according to the voltage of the to-be-balanced single cell indicated by the identifier of the to-be-balanced single cell and a preset reference voltage; according to the equalization instruction and the voltage detection signal, generating a charging and discharging protection signal corresponding to the to-be-equalized single cell; and according to the charging and discharging protection signal, generating an equalization protection signal corresponding to the to-be-equalized single cell, and cutting off an equalization module power supply through the equalization protection signal so as to control the equalization module to stop running. According to the invention, the effects of preventing the battery cells from being overcharged or overdischarged in the active equalization process and reducing the maintenance difficulty of the battery management system can be achieved.

Description

Technical Field

[0001] The present application relates to the technical field of battery cell balancing, and in particular to a method for balancing overvoltage and undervoltage of battery cells, a battery management system and a vehicle. Background Art

[0002] The energy storage system is composed of multiple battery packs, which are implemented by multiple single cells. However, due to differences in the factory configuration of each single cell and self-discharge during use, the power of each single cell is inconsistent, which affects the overall performance and service life of the battery pack. However, although the inconsistency between the single cells can be reduced by active balancing, the balancing current output by active balancing is large, and the cell voltage cannot be effectively sampled during the balancing process, which can easily lead to the risk of overcharging or over-discharging the cell. Therefore, a cell protection circuit is urgently needed to prevent the battery cell from being overcharged or over-discharged during the active balancing process.

[0003] In the related art, a cell voltage protection circuit can generally be deployed in a battery management system. The cell protection circuit can timely cut off the equalization circuit during the active equalization process of the battery cells to avoid overcharging or over-discharging of the battery cells. When the cell voltage is too high or too low, the cell protection circuit timely cuts off the voltage equalization circuit by outputting a hardware protection signal to achieve over-voltage and under-voltage protection of the battery cells.

[0004] However, when performing cell protection based on the related technology, when the cell voltage is too high or too low, the charge and discharge balancing circuits of the cell are prohibited, and the balanced single cell cannot be charged or discharged through the balancing module. The battery pack needs to be disassembled and the charging and discharging equipment needs to be used to charge or discharge the balanced single cell to remedy the problem. Therefore, the related technology solution has the problem of high difficulty in maintaining the battery management system. Summary of the invention

[0005] The purpose of the present application is to provide a method for balancing overvoltage and undervoltage of battery cells, a battery management system and a vehicle, which can prevent the battery cells from being overcharged or over-discharged during active balancing and reduce the difficulty of maintaining the battery management system.

[0006] The embodiment of the present application is implemented as follows:

[0007] In a first aspect of an embodiment of the present application, a method for balancing overvoltage and undervoltage of a battery cell and a battery management system are provided. The method is applied to a battery management unit in the battery management system. The battery management system includes: a cluster management unit and a battery management unit. The battery management unit includes: a controller, a balancing module, and a balancing module power supply. The battery management unit manages voltage sampling and balancing of each battery group composed of multiple single cells. The method includes:

[0008] Receive the balancing instruction sent by the host computer and collect the voltage of each single cell in each battery pack in real time. The balancing instruction includes: the identification of the single cell to be balanced, the charging balancing instruction or the discharging balancing instruction;

[0009] Generate a voltage detection signal corresponding to the single cell to be balanced according to the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced and a preset reference voltage, the voltage detection signal includes: an overvoltage signal or an undervoltage signal;

[0010] Generate a charge and discharge protection signal corresponding to the single cell to be balanced according to the equalization instruction and the voltage detection signal, the charge and discharge protection signal includes: an overvoltage charge protection signal or an undervoltage discharge protection signal;

[0011] According to the charge and discharge protection signal corresponding to the single cell to be balanced, a balancing protection signal corresponding to the single cell to be balanced is generated, and the power supply of the balancing module is cut off through the balancing protection signal to control the balancing module to stop running.

[0012] As a possible implementation, generating a voltage detection signal corresponding to the single cell to be balanced according to the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced and a preset reference voltage includes:

[0013] Determine an overvoltage signal corresponding to the single cell to be balanced according to a comparison result of the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced and a maximum value of preset reference voltages;

[0014] According to the comparison result of the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced and the minimum value of the preset reference voltage, the undervoltage signal corresponding to the single cell to be balanced is determined.

[0015] As a possible implementation, determining the overvoltage signal corresponding to the single cell to be balanced according to the comparison result between the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced and the maximum value of the preset reference voltage includes:

[0016] If the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced is greater than the maximum value of the preset reference voltage, the overvoltage signal corresponding to the single cell to be balanced is at a low level;

[0017] If the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced is less than or equal to the maximum value of the preset reference voltages, the overvoltage signal corresponding to the single cell to be balanced is at a high level.

[0018] As a possible implementation, determining the undervoltage signal corresponding to the single cell to be balanced according to the comparison result between the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced and the maximum value of the preset reference voltage includes:

[0019] If the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced is less than the minimum value of the preset reference voltage, the undervoltage signal corresponding to the single cell to be balanced is at a high level;

[0020] If the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced is greater than or equal to the minimum value of the preset reference voltages, the undervoltage signal corresponding to the single cell to be balanced is at a low level.

[0021] As a possible implementation method, a charge and discharge protection signal corresponding to the single cell to be balanced is generated according to the balancing instruction and the voltage detection signal, including:

[0022] If the balancing instruction is a charging balancing instruction, and the voltage detection signal corresponding to the single cell to be balanced is an overvoltage signal, then the charge and discharge protection signal corresponding to the single cell to be balanced is an overvoltage charging protection signal;

[0023] If the balancing instruction is a discharge balancing instruction, and the voltage detection signal corresponding to the single cell to be balanced is an undervoltage signal, then the charge and discharge protection signal corresponding to the single cell to be balanced is an undervoltage discharge protection signal.

[0024] As a possible implementation method, the charge and discharge protection signal corresponding to the single cell to be balanced is an overvoltage charge protection signal, including:

[0025] If the overvoltage signal corresponding to the single cell to be balanced is at a low level, and the received balancing instruction is a charging balancing instruction, the overvoltage charging protection signal corresponding to the single cell to be balanced is at a low level;

[0026] If the overvoltage signal corresponding to the single cell to be balanced is at a high level, and the received balancing instruction is a charging balancing instruction, the overvoltage charging protection signal corresponding to the single cell to be balanced is at a high level.

[0027] As a possible implementation method, the charge and discharge protection signal corresponding to the single cell to be balanced is an undervoltage discharge protection signal, including:

[0028] If the undervoltage signal corresponding to the single cell to be balanced is at a high level, and the received balancing instruction is a discharge balancing instruction, the undervoltage discharge protection signal corresponding to the single cell to be balanced is at a low level;

[0029] If the undervoltage signal corresponding to the single cell to be balanced is at a low level, and the received balancing instruction is a discharge balancing instruction, the undervoltage discharge protection signal corresponding to the single cell to be balanced is at a high level.

[0030] As a possible implementation method, according to the charge and discharge protection signal corresponding to the single cell to be balanced, a balancing protection signal corresponding to the single cell to be balanced is generated, and the power supply of the balancing module is cut off through the balancing protection signal to control the balancing module to stop running, including:

[0031] If the overvoltage charging protection signal corresponding to the single cell to be balanced is at a low level or the undervoltage discharge protection signal corresponding to the single cell to be balanced is at a low level, a balancing protection signal corresponding to the single cell to be balanced is generated, and the power supply of the balancing module is cut off through the balancing protection signal to control the balancing module to stop running.

[0032] In a second aspect of an embodiment of the present application, a battery management system is provided, the battery management system comprising: a cluster management unit and a battery management unit, the battery management unit comprising: a controller, a balancing module and a balancing module power supply, the battery management unit managing voltage sampling and balancing of each battery group composed of a plurality of single cells;

[0033] The battery management unit in the battery management system is used to execute the steps of the method for balancing overvoltage and undervoltage of battery cells described in the first aspect above.

[0034] According to a third aspect of an embodiment of the present application, a vehicle is provided, in which the battery management system described in the second aspect is deployed.

[0035] The beneficial effects of the embodiments of the present application include:

[0036] A method for balancing overvoltage and undervoltage of battery cells provided in an embodiment of the present application receives a balancing instruction issued by a host computer through a controller in a battery management system, and collects the voltage of each single battery cell in each battery group in the battery management system in real time; determines a voltage detection signal corresponding to the single battery cell to be balanced according to a comparison result between the voltage of the single battery cell to be balanced indicated by the identifier of the single battery cell to be balanced in the balancing instruction and a preset reference voltage, and the voltage detection signal is used to indicate that the single battery cell to be balanced is in an overcharge state or an over-discharge state; generates a charge and discharge protection signal corresponding to the single battery cell to be balanced according to a matching relationship between the voltage detection signal corresponding to the single battery cell to be balanced and the received balancing instruction, and the charge and discharge protection signal is used to indicate a charge and discharge limit signal corresponding to the single battery cell to be balanced; generates a balancing protection signal corresponding to the single battery cell to be balanced according to the charge and discharge protection signal corresponding to the single battery cell to be balanced, and cuts off the power supply of the balancing module through the balancing protection signal to control the balancing module to stop running, so as to prevent the balancing circuit from continuing to charge and balance or discharge and balance the battery cell that is already in an overcharge state or an over-discharge state. Among them, if the voltage detection signal of the single cell to be balanced is an overvoltage signal, but the balancing instruction received by the controller is a charging balancing instruction, then the charge and discharge protection signal corresponding to the single cell to be balanced is an overvoltage charging protection signal. Based on the overvoltage charging protection signal, the controller cuts off the connection between the balancing module power supply and the balancing module, and stops the balancing module from continuing to charge and balance the overvoltage single cell to be balanced, and vice versa. In this way, the battery cells can be prevented from being overcharged or over-discharged during the active balancing process, and the difficulty of maintaining the battery management system can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 A schematic diagram of the structure of a battery management system provided in an embodiment of the present application;

[0039] Figure 2 A flow chart of a first method for balancing overvoltage and undervoltage of a battery cell provided in an embodiment of the present application;

[0040] Figure 3 A flow chart of a second method for balancing overvoltage and undervoltage of battery cells provided in an embodiment of the present application;

[0041] Figure 4 A flowchart of a third method for balancing overvoltage and undervoltage of battery cells provided in an embodiment of the present application;

[0042] Figure 5 A flowchart of a fourth method for balancing overvoltage and undervoltage of battery cells provided in an embodiment of the present application;

[0043] Figure 6 A flowchart of a fifth method for balancing overvoltage and undervoltage of battery cells provided in an embodiment of the present application;

[0044] Figure 7 A flowchart of a sixth method for balancing overvoltage and undervoltage of battery cells provided in an embodiment of the present application;

[0045] Figure 8 A flowchart of a seventh method for balancing overvoltage and undervoltage of battery cells provided in an embodiment of the present application;

[0046] Fig. 9 A system block diagram of balancing overvoltage and undervoltage of battery cells provided in an embodiment of the present application;

[0047] Fig.10 A cell overvoltage detection circuit diagram provided in an embodiment of the present application;

[0048] Fig.11 A cell undervoltage detection circuit diagram provided in an embodiment of the present application;

[0049] Fig.12 A cell over-voltage and under-voltage balancing circuit diagram provided in an embodiment of the present application;

[0050] Fig.13 A schematic diagram of the structure of a vehicle provided in an embodiment of the present application. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0052] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0053] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0054] At present, the cell voltage protection circuit is often deployed in the battery management system. The cell voltage protection circuit monitors the voltage of each single cell in the process of active balancing of the battery pack in real time, and outputs a hardware protection signal when the cell voltage is too high or too low, and cuts off the voltage balancing circuit in time to prevent the active balancing from causing overcharging or over-discharging of the cell. However, this solution has the problem that the charge and discharge balancing module is prohibited when the cell voltage is too high or too low, and the balancing module cannot be used to manage overvoltage discharge or undervoltage charging of the single cell. The battery pack needs to be disassembled and the single cell needs to be remedied by overvoltage discharge and undervoltage charging with the help of external charging and discharging equipment, which makes the battery management system difficult to repair.

[0055] To this end, the embodiment of the present application provides a method for balancing overvoltage and undervoltage of battery cells, by receiving the balancing instruction issued by the host computer and collecting the voltage of each single cell in each battery pack in real time; generating a voltage detection signal corresponding to the single cell to be balanced according to the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced in the balancing instruction and a preset reference voltage, and generating a charge and discharge protection signal corresponding to the single cell to be balanced according to the balancing instruction and the voltage detection signal corresponding to the single cell to be balanced, and then generating a balancing protection signal corresponding to the single cell to be balanced according to the charge and discharge protection signal corresponding to the single cell to be balanced, and cutting off the power supply of the balancing module based on the balancing protection signal corresponding to the single cell to be balanced to control the balancing module to stop running. In this way, the battery cells can be prevented from being overcharged or over-discharged during the active balancing process, and the difficulty of maintaining the battery management system can be reduced.

[0056] The following is a detailed explanation of the method for balancing overvoltage and undervoltage of battery cells, the battery management system and the vehicle provided in the embodiments of the present application in conjunction with the accompanying drawings.

[0057] Figure 1 A battery management system provided for this application, see Figure 1 A battery management system 10 provided in an embodiment of the present application includes: a cluster management unit 101 and a battery management unit 102. The battery management unit 102 includes: a controller 1021, a balancing module 1022, and a balancing module power supply 1023. The battery management unit 102 manages the voltage sampling and balancing of each battery group 1011 composed of multiple single cells 111. Among them, the controller 1021 in the battery management unit 102 is respectively connected to the balancing module power supply 1023 and each battery group 1011 for communication, and the controller 1021 is also connected to the host computer for communication. Each balancing module 1022 in the battery management unit 102 is respectively connected to a battery group 1011.

[0058] Optionally, the balancing module power supply 1023 and the balancing module 1022 together constitute an active balancing circuit of the battery management system 10, the balancing module power supply 1023 is used to supply power to the balancing module 1022, and the balancing module 1022 is used to balance the voltage of each single cell 111 in each battery pack 1011. Among them, the battery management system 10 receives the balancing instruction issued by the upper computer via the controller 1021, and the controller 1021 collects the voltage of each single cell 111 in each battery pack 1011 in real time while receiving the balancing instruction. The controller 1021 determines the overvoltage state and undervoltage state of each single cell 111 based on the real-time voltage of each single cell 111, and determines whether the charge and discharge balancing mode indicated by the balancing instruction can remedy the overvoltage state or undervoltage state of the single cell to be balanced indicated by the identifier of the balanced single cell in the balancing instruction. If the charge and discharge balancing mode indicated by the balancing instruction If the charge balancing mode can remedy the overvoltage state or undervoltage state of the single cell to be balanced, the active balancing circuit operates normally, and the balancing module 1022 normally performs charge balancing or discharge balancing on the single cell to be balanced; on the contrary, if the charge and discharge balancing mode indicated by the balancing instruction cannot remedy the overvoltage state or undervoltage state of the single cell to be balanced, and will further aggravate the overvoltage state or undervoltage state of the single cell to be balanced, the controller 1021 cuts off the balancing module power supply 1023 to control the balancing module 1022 to stop charging balancing or discharging balancing of the single cell to be balanced.

[0059] Optionally, the battery management system 10 includes multiple balancing modules 1022, and the balancing module power supply 1023 can be in a one-to-one relationship with the balancing module 1022, and the balancing module power supply 1023 can also be associated with multiple balancing modules 1022 at the same time, and this application does not make specific restrictions on this. It is worth noting that one balancing module 1022 is connected to one battery pack 1011, that is, one balancing module 1022 can perform voltage balancing on multiple single cells contained in one battery pack 104.

[0060] Figure 2 This is a flow chart of a method for balancing overvoltage and undervoltage of a battery cell provided in the present application. The method can be applied to a battery management unit in a battery management system. Figure 2 , the embodiment of the present application provides a method for balancing overvoltage and undervoltage of a battery cell, comprising:

[0061] S201, receiving a balancing instruction sent by a host computer, and collecting the voltage of each single cell in each battery pack in real time, wherein the balancing instruction includes: an identification of the single cell to be balanced, a charging balancing instruction or a discharging balancing instruction.

[0062] Optionally, the balancing instruction refers to the charge and discharge balancing control instruction issued by the host computer. The balancing instruction is used to control the balancing mode of the balancing circuit and control the active balancing circuit to perform voltage balancing on the specified single cell to be balanced. The balancing module in the battery management system performs voltage balancing on the specified single cell to be balanced in the battery pack under the action of the balancing instruction. The balancing module divides the balancing mode of the single cell to be balanced into charging balancing and discharging balancing. Among them, the balancing instruction includes: the identification of the single cell to be balanced, the charging balancing instruction or the discharging balancing instruction. The identification of the single cell to be balanced is used to indicate the host computer to specify the number of the single cell to be balanced for the active balancing circuit to perform voltage balancing. The charging balancing instruction is a control command for instructing the balancing module to perform charging balancing on the specified single cell to be balanced. The discharging balancing instruction is a control command for instructing the balancing module to perform discharging balancing on the specified single cell to be balanced.

[0063] Optionally, after receiving the balancing instruction issued by the upper computer, the controller in the battery management system synchronously and in real time collects the voltage of each single cell in each battery group in the battery management system, and determines in real time whether the single cell to be balanced indicated by the identifier of the single cell to be balanced in the balancing instruction has an over-voltage or under-voltage condition, and whether the charge and discharge balancing mode indicated by the balancing module can cure the over-voltage or under-voltage condition of the single cell to be balanced. If the charge and discharge balancing mode indicated by the balancing instruction will aggravate the over-voltage or under-voltage condition of the single cell to be balanced, it is determined that there is a hardware circuit failure in the battery management system, and the controller cuts off the connection between the power supply of the balancing module and the balancing module, and reports the fault information; conversely, if the charge and discharge balancing mode indicated by the balancing instruction can remedy the over-voltage or under-voltage condition of the single cell to be balanced, it is determined that there is no hardware circuit failure in the battery management system, and the active balancing circuit operates normally.

[0064] S202 , generating a voltage detection signal corresponding to the single cell to be balanced according to the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced and a preset reference voltage, wherein the voltage detection signal includes: an overvoltage signal or an undervoltage signal.

[0065] Optionally, the preset reference voltage is the voltage range of the normal operation of each single cell in the battery pack set in advance by the user. The preset reference voltage includes the maximum voltage value and the minimum voltage value of the normal operation of the single cell. When the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced in the balancing instruction is higher than the maximum voltage value indicated by the preset reference voltage, the single cell to be balanced is in an overvoltage state, that is, the single cell to be balanced is in an overcharge state; when the voltage of the single cell to be balanced is lower than the minimum voltage value indicated by the preset reference voltage, the single cell to be balanced is in an undervoltage state, that is, the single cell to be balanced is in an over-discharge state. Among them, the overvoltage state is used to indicate that the voltage of the single cell to be balanced is too high, the overcharge state is used to indicate that the charge currently contained in the single cell to be balanced exceeds the limit of the amount of electricity that the single cell to be balanced can contain, the undervoltage state is used to indicate that the voltage of the single cell to be balanced is too low, and the over-discharge state is used to indicate that the electricity consumption of the single cell to be balanced is serious.

[0066] Optionally, the controller generates a voltage detection signal corresponding to the single cell to be balanced according to the comparison result between the real-time voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced in the balancing instruction and the preset reference voltage, and the voltage detection signal is used to indicate the voltage detection result of the single cell to be balanced. Among them, the voltage detection signal includes: an overvoltage signal or an undervoltage signal, the overvoltage signal is used to indicate that the voltage of the single cell to be balanced is too high, and the undervoltage signal is used to indicate that the voltage of the single cell to be balanced is too low. In addition, the voltage of the single cell to be balanced can also be within the voltage range indicated by the preset reference voltage. When the voltage of the single cell to be balanced is within the voltage range indicated by the preset reference voltage, the single cell to be balanced can be applicable to various charge and discharge balancing modes, that is, the balancing module can perform both charge balancing and discharge balancing on the single cell to be balanced. It is worth noting that it is impossible for the single cell to be balanced to exist in both overvoltage and undervoltage states at the same time, that is, the voltage detection signal corresponding to the single cell to be balanced can only be one of the overvoltage signal or the undervoltage signal. The voltage detection signal corresponding to the single cell to be balanced is specifically determined by the real-time voltage of the single cell to be balanced, and this application does not make any specific limitation on this.

[0067] S203 , generating a charge and discharge protection signal corresponding to the single cell to be balanced according to the equalization instruction and the voltage detection signal, wherein the charge and discharge protection signal includes an overvoltage charge protection signal or an undervoltage discharge protection signal.

[0068] Optionally, the controller generates a charge and discharge protection signal corresponding to the single cell to be balanced according to the charge and discharge balancing mode indicated by the received balancing instruction and the voltage detection result of the single cell to be balanced. The charge and discharge protection signal is used to indicate the charge and discharge limit signal corresponding to the single cell to be balanced. The charge and discharge protection signal includes: an overvoltage charging protection signal or an undervoltage discharge protection signal. The overvoltage charging protection signal is used to indicate that the balancing module is prohibited from performing charge balancing on the single cell to be balanced in an overvoltage state, and the undervoltage discharge protection signal is used to indicate that the balancing module is prohibited from performing charge balancing on the single cell to be balanced in an undervoltage state. For example, when the voltage detection signal corresponding to the single cell to be balanced is an overvoltage signal, the controller prohibits the balancing module from performing charge balancing on the single cell to be balanced, but allows the balancing module to discharge the single cell to be balanced to remedy the overvoltage state of the single cell to be balanced; for example, when the voltage detection signal corresponding to the single cell to be balanced is an undervoltage signal, the controller prohibits the balancing module from performing discharge balancing on the single cell to be balanced, but allows the balancing module to charge the single cell to be balanced to remedy the undervoltage state of the single cell to be balanced.

[0069] S204 , generating a balancing protection signal corresponding to the single battery cell to be balanced according to the charge and discharge protection signal corresponding to the single battery cell to be balanced, and cutting off the power supply of the balancing module through the balancing protection signal to control the balancing module to stop running.

[0070] Optionally, the controller generates a balancing protection signal corresponding to the single cell to be balanced based on the charge and discharge protection signal corresponding to the single cell to be balanced. The balancing protection signal is also a cut-off signal or a circuit breaker signal of the balancing module power supply. The balancing protection signal can prevent the cell that is already in an overcharged or over-discharged state from continuing to charge or discharge balance.

[0071] Optionally, the controller cuts off the power supply of the balancing module through the balancing protection signal and continues to supply power to the balancing module, so that the balancing module stops performing charge balancing or discharge balancing on the single cells to be balanced in the battery pack.

[0072] In an embodiment of the present application, a controller in a battery management system receives a balancing instruction issued by a host computer, and collects the voltage of each single cell in each battery group in the battery management system in real time; a voltage detection signal corresponding to the single cell to be balanced is determined according to a comparison result between the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced in the balancing instruction and a preset reference voltage, and the voltage detection signal is used to indicate that the single cell to be balanced is in an overcharge state or an over-discharge state; a charge and discharge protection signal corresponding to the single cell to be balanced is generated according to a matching relationship between the voltage detection signal corresponding to the single cell to be balanced and the received balancing instruction, and the charge and discharge protection signal is used to indicate a charge and discharge limit signal corresponding to the single cell to be balanced; a balancing protection signal corresponding to the single cell to be balanced is generated according to the charge and discharge protection signal corresponding to the single cell to be balanced, and the balancing module power supply is cut off through the balancing protection signal to control the balancing module to stop running, so as to prevent the balancing circuit from continuing to charge and balance or discharge and balance the cell that is already in an overcharge state or an over-discharge state. Among them, if the voltage detection signal of the single cell to be balanced is an overvoltage signal, but the balancing instruction received by the controller is a charging balancing instruction, then the charge and discharge protection signal corresponding to the single cell to be balanced is an overvoltage charging protection signal. Based on the overvoltage charging protection signal, the controller cuts off the connection between the balancing module power supply and the balancing module, and stops the balancing module from continuing to charge and balance the overvoltage single cell to be balanced, and vice versa. In this way, the battery cells can be prevented from being overcharged or over-discharged during the active balancing process, and the difficulty of maintaining the battery management system can be reduced.

[0073] For a possible implementation, see Figure 3 The operation of step S202 may specifically be:

[0074] S301 : Determine an overvoltage signal corresponding to the single cell to be balanced according to a comparison result between the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced and a maximum value of preset reference voltages.

[0075] Optionally, the maximum value of the preset reference voltage is the maximum load of the voltage that the single cell can accommodate, which is set by the user according to the production specifications of each single cell in the battery pack. According to whether the real-time voltage of the single cell to be balanced indicated by the identification of the single cell to be balanced exceeds the maximum value of the preset reference voltage, the overvoltage signal corresponding to the single cell to be balanced can be determined. The overvoltage signal is used to indicate the overvoltage condition of the single cell to be balanced. If the real-time voltage of the single cell to be balanced indicated by the identification of the single cell to be balanced exceeds the limit of the maximum value of the preset reference voltage, the single cell to be balanced is in an overvoltage state; if the real-time voltage of the single cell to be balanced indicated by the identification of the single cell to be balanced does not exceed the limit of the maximum value of the preset reference voltage, the single cell to be balanced does not exist in an overvoltage state. It is worth noting that regardless of whether the real-time voltage of the single cell to be balanced indicated by the identification of the single cell to be balanced exceeds the maximum value of the preset reference voltage, the controller will generate an overvoltage signal corresponding to the single cell to be balanced, but the controller will set the level corresponding to the overvoltage signal according to whether the single cell to be balanced is actually in an overvoltage state.

[0076] S302 : Determine an undervoltage signal corresponding to the single cell to be balanced according to a comparison result between the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced and a minimum value of preset reference voltages.

[0077] Optionally, the minimum value of the preset reference voltage is the minimum limit of the safe discharge of the single cell set by the user according to the production specifications of the single cell. When the real-time voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced reaches the minimum value of the preset reference voltage, if the single cell to be balanced is still discharged, the single cell to be balanced will be damaged, thereby shortening the service life of the battery pack where the single cell to be balanced is located.

[0078] Optionally, according to whether the real-time voltage of the single cell to be balanced indicated by the identification of the single cell to be balanced is lower than the minimum value in the preset reference voltage, the undervoltage signal corresponding to the single cell to be balanced can be determined, and the undervoltage signal is used to indicate the undervoltage condition of the single cell to be balanced. If the real-time voltage of the single cell to be balanced indicated by the identification of the single cell to be balanced is lower than the limit of the maximum value in the preset reference voltage, the single cell to be balanced is in an undervoltage state; if the real-time voltage of the single cell to be balanced indicated by the identification of the single cell to be balanced is higher than the limit of the minimum value in the preset reference voltage, the single cell to be balanced is not in an undervoltage state. It is worth noting that regardless of whether the real-time voltage of the single cell to be balanced indicated by the identification of the single cell to be balanced is lower than the maximum value in the preset reference voltage, the controller will generate an undervoltage signal corresponding to the single cell to be balanced, but the controller will set the level corresponding to the undervoltage signal according to whether the single cell to be balanced is actually in an undervoltage state.

[0079] It is worth noting that the fact that the real-time voltage of the single cell to be balanced indicated by the identification of the single cell to be balanced does not exceed the maximum value of the preset reference voltage does not mean that the single cell to be balanced is operating normally. The real-time voltage of the single cell to be balanced does not exceed the maximum value of the preset reference voltage. The real-time voltage of the single cell to be balanced may be lower than the minimum value of the preset reference voltage.

[0080] For a possible implementation, see Figure 4 The operation of step S301 may specifically be:

[0081] S401: If the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced is greater than the maximum value of the preset reference voltage, the overvoltage signal corresponding to the single cell to be balanced is at a low level.

[0082] Optionally, the low level can be represented by 0, that is, the overvoltage signal corresponding to the single cell to be balanced is at a low level, which can be represented by the overvoltage signal corresponding to the single cell to be balanced being 0. When the real-time voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced exceeds the maximum value limit of the preset reference voltage, the single cell to be balanced actually has an overvoltage condition, and the controller marks the overvoltage signal corresponding to the single cell to be balanced as 0. The overvoltage signal is at a low level to indicate that the single cell to be balanced actually has an overvoltage condition, or the single cell to be balanced actually has an overvoltage condition.

[0083] S402: If the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced is less than or equal to the maximum value of the preset reference voltage, the overvoltage signal corresponding to the single cell to be balanced is at a high level.

[0084] Optionally, a high level can be represented by 1, that is, the overvoltage signal corresponding to the single cell to be balanced is a high level, which can be represented by the overvoltage signal corresponding to the single cell to be balanced being 1. When the real-time voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced does not exceed the maximum value of the preset reference voltage, the single cell to be balanced does not have an overvoltage condition, and the controller marks the overvoltage signal corresponding to the single cell to be balanced as 1. The high level of the overvoltage signal is used to indicate that the single cell to be balanced does not have an overvoltage condition.

[0085] For a possible implementation, see Figure 5 The operation of step S302 may specifically be:

[0086] S501: If the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced is less than the minimum value of the preset reference voltage, the undervoltage signal corresponding to the single cell to be balanced is at a high level.

[0087] Optionally, the undervoltage signal corresponding to the single cell to be balanced is at a high level, which can be represented by the undervoltage signal corresponding to the single cell to be balanced being 1. When the real-time voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced is lower than the minimum value of the preset reference voltage, the single cell to be balanced actually has an undervoltage condition, and the controller marks the undervoltage signal corresponding to the single cell to be balanced as 1. The undervoltage signal is at a high level and is used to characterize that the single cell to be balanced actually has an undervoltage condition, or that the single cell to be balanced actually has a voltage condition that is too low.

[0088] S502: If the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced is greater than or equal to the minimum value of the preset reference voltage, the undervoltage signal corresponding to the single cell to be balanced is at a low level.

[0089] Optionally, the undervoltage signal corresponding to the single cell to be balanced is at a low level, which can be represented by the undervoltage signal corresponding to the single cell to be balanced being 0. When the real-time voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced is higher than the minimum value limit of the preset reference voltage, the single cell to be balanced does not have an undervoltage condition, and the controller marks the undervoltage signal corresponding to the single cell to be balanced as 0. The undervoltage signal is at a low level to indicate that the single cell to be balanced does not have an undervoltage condition.

[0090] For a possible implementation, see Figure 6 The operation of step S203 may specifically be:

[0091] S601: If the balancing instruction is a charging balancing instruction, and the voltage detection signal corresponding to the single battery cell to be balanced is an overvoltage signal, then the charge and discharge protection signal corresponding to the single battery cell to be balanced is an overvoltage charging protection signal.

[0092] Optionally, when the balancing instruction received by the controller in the battery management system is used to instruct the balancing circuit to charge and balance the single cells to be balanced in the battery pack, but the voltage detection signal indicated by the comparison result of the real-time voltage of the single cell to be balanced with a preset reference voltage is an overvoltage signal, the controller in the battery management system generates a charge and discharge protection signal corresponding to the single cell to be balanced as an overvoltage charging protection signal, and the overvoltage charging protection signal is used to limit the balancing module from continuing to charge and balance the single cell to be balanced in an overvoltage state, thereby further preventing the single cell to be balanced from overcharging.

[0093] S602: If the balancing instruction is a discharge balancing instruction, and the voltage detection signal corresponding to the single battery cell to be balanced is an undervoltage signal, the charge and discharge protection signal corresponding to the single battery cell to be balanced is an undervoltage discharge protection signal.

[0094] Optionally, when the balancing instruction received by the controller in the battery management system is used to instruct the balancing circuit to discharge and balance the single cells to be balanced in the battery pack, but the voltage detection signal indicated by the comparison result of the real-time voltage of the single cell to be balanced with a preset reference voltage is an undervoltage signal, the controller in the battery management system generates a charge and discharge protection signal corresponding to the single cell to be balanced as an undervoltage discharge protection signal, and the undervoltage discharge protection signal is used to limit the balancing module from continuing to discharge and balance the single cell to be balanced in the undervoltage state, thereby further preventing the single cell to be balanced from overdischarging.

[0095] For a possible implementation, see Figure 7 The operation of step S601 may specifically be:

[0096] S701: If the overvoltage signal corresponding to the single cell to be balanced is at a low level, and the received balancing instruction is a charging balancing instruction, the overvoltage charging protection signal corresponding to the single cell to be balanced is at a low level.

[0097] Optionally, when the overvoltage signal corresponding to the single cell to be balanced is at a low level, that is, the single cell to be balanced is currently in an overvoltage state, and the balancing instruction received by the controller in the battery management system instructs the balancing module to charge and balance the single cell to be balanced, the overvoltage charging protection signal corresponding to the single cell to be balanced generated by the controller in the battery management system is at a low level. The overvoltage charging protection signal being at a low level can also be represented by an overvoltage charging protection signal of 0. The overvoltage charging protection signal being at a low level is used to limit the balancing module from continuing to charge and balance the single cell to be balanced that is in an overvoltage state.

[0098] S702: If the overvoltage signal corresponding to the single cell to be balanced is at a high level, and the received balancing instruction is a charging balancing instruction, the overvoltage charging protection signal corresponding to the single cell to be balanced is at a high level.

[0099] Optionally, when the overvoltage signal corresponding to the single cell to be balanced is at a high level, that is, the single cell to be balanced currently does not have an overvoltage condition, and the single cell to be balanced may currently be operating normally or in an undervoltage condition. At this time, when the balancing instruction received by the controller in the battery management system instructs the balancing module to charge and balance the single cell to be balanced, the overvoltage charging protection signal corresponding to the single cell to be balanced generated by the controller in the battery management system is at a high level. The overvoltage charging protection signal being at a high level can also be represented by an overvoltage charging protection signal of 1. The overvoltage charging protection signal being at a high level is used to allow the balancing module to continue to charge and balance the single cell to be balanced.

[0100] For a possible implementation, see Figure 8 The operation of step S602 may specifically be:

[0101] S801: If the undervoltage signal corresponding to the single cell to be balanced is at a high level and the received balancing instruction is a discharge balancing instruction, the undervoltage discharge protection signal corresponding to the single cell to be balanced is at a low level.

[0102] Optionally, when the undervoltage signal corresponding to the single cell to be balanced is at a high level, that is, the single cell to be balanced is currently in an undervoltage state, and the balancing instruction received by the controller in the battery management system instructs the balancing module to discharge and balance the single cell to be balanced, the undervoltage discharge protection signal corresponding to the single cell to be balanced generated by the controller in the battery management system is at a low level. The undervoltage discharge protection signal being at a low level can also be represented by the undervoltage discharge protection signal being 0. The undervoltage discharge protection signal being at a low level is used to limit the balancing module from continuing to discharge and balance the single cell to be balanced that is in an undervoltage state.

[0103] S802: If the undervoltage signal corresponding to the single cell to be balanced is at a low level, and the received balancing instruction is a discharge balancing instruction, the undervoltage discharge protection signal corresponding to the single cell to be balanced is at a high level.

[0104] Optionally, when the undervoltage signal corresponding to the single cell to be balanced is at a low level, that is, the single cell to be balanced currently does not have an undervoltage condition, that is, the single cell to be balanced may currently be in a normal operating state or may be in an overvoltage state, at this time, when the balancing instruction received by the controller in the battery management system instructs the balancing module to discharge and balance the single cell to be balanced, the undervoltage discharge protection signal corresponding to the single cell to be balanced generated by the controller in the battery management system is at a high level. The undervoltage discharge protection signal being at a high level can also be represented by the undervoltage discharge protection signal being 1, and the undervoltage discharge protection signal being at a high level is used to allow the balancing module to continue to discharge and balance the single cell to be balanced.

[0105] In a possible implementation, the operation of step S204 may specifically be:

[0106] If the overvoltage charging protection signal corresponding to the single cell to be balanced is at a low level or the undervoltage discharge protection signal corresponding to the single cell to be balanced is at a low level, a balancing protection signal corresponding to the single cell to be balanced is generated, and the power supply of the balancing module is cut off through the balancing protection signal to control the balancing module to stop running.

[0107] Optionally, when the overvoltage charging protection signal corresponding to the single cell to be balanced is at a low level or the undervoltage discharge protection signal corresponding to the single cell to be balanced is at a low level, that is, the overvoltage charging protection signal corresponding to the single cell to be balanced is 0 or the undervoltage discharge protection signal corresponding to the single cell to be balanced is 0, it indicates that the single cell to be balanced currently has a voltage that is too high or a voltage that is too low, that is, the single cell to be balanced is in an overvoltage state or an undervoltage state.

[0108] Optionally, when the single cell to be balanced is actually in an overvoltage state or an undervoltage state, the controller in the battery management system generates a balancing protection signal corresponding to the single cell to be balanced. The balancing protection signal is used to protect the single cell to be balanced in the overvoltage state from continuing to be overcharged or to protect the single cell to be balanced in the undervoltage state from continuing to be over-discharged. The balancing protection signal is a low level, that is, the balancing protection signal can be represented by 0.

[0109] Optionally, the controller in the battery management system sends a balancing protection signal to the enable end of the balancing module power supply. Under the action of the balancing protection signal, the balancing module power supply is disconnected from the balancing module, and the balancing module stops charging the over-voltage single battery cell to be balanced or stops discharging and balancing the under-voltage single battery cell to be balanced.

[0110] In an optional implementation, Fig. 9 A system block diagram for balancing overvoltage and undervoltage of battery cells provided in this application, see Fig. 9 The specific implementation process of balancing overvoltage and undervoltage of battery cells provided in the present application is as follows: S1. When the controller in the battery management system receives the balancing instruction issued by the upper computer, it synchronously and in real time collects the voltage of each single battery cell in each battery group in the battery management system; S2. According to the real-time voltage of the single battery cell to be balanced indicated by the identifier of the single battery cell to be balanced in the balancing instruction and the preset reference voltage, it is judged whether the single battery cell to be balanced exists in an overvoltage or undervoltage state, and according to the over-voltage or undervoltage state of the single battery cell to be balanced, an overvoltage signal or undervoltage signal corresponding to the single battery cell to be balanced is generated; S3. The controller in the battery management system collects the voltage of each single battery cell in each battery group in the battery management system synchronously and in real time; S4. According to the real-time voltage of the single battery cell to be balanced indicated by the identifier of the single battery cell to be balanced in the balancing instruction and the preset reference voltage, it is judged whether the single battery cell to be balanced exists in an overvoltage or undervoltage state, and according to the over-voltage or undervoltage state of the single battery cell to be balanced, an overvoltage signal or undervoltage signal corresponding to the single battery cell to be balanced is generated; S5. The battery management system uses the voltage detection signal of the single cell to be balanced as well as the instruction to judge whether the balancing mode indicated by the balancing instruction can control the overvoltage or undervoltage condition of the single cell to be balanced, and generates an overvoltage charging protection signal or an undervoltage discharge protection signal corresponding to the single cell to be balanced according to the judgment result; S4, generates a balancing protection signal corresponding to the single cell to be balanced according to the overvoltage charging protection signal or the undervoltage discharge protection signal corresponding to the single cell to be balanced, and the battery management system cuts off the power supply of the balancing module through the balancing protection signal to control the balancing module to stop running, so as to prevent the overvoltage single cell to be balanced from continuing to be overcharged or the undervoltage single cell to be balanced from continuing to be over-discharged.

[0111] In an optional implementation, Fig.10 For a cell overvoltage detection circuit diagram provided in this application, see Fig.10, a cell overvoltage detection circuit provided in an embodiment of the present application includes multiple capacitors, multiple resistors and a comparator. Among them, VCC_F7V0_1 is the power supply voltage provided by the power supply, DCDC1_V+ refers to the real-time voltage of each single cell, and the controller in the battery management system determines whether there is an overvoltage condition in the single cell to be balanced based on the cell overvoltage detection circuit, and outputs an overvoltage signal OV_OUT.

[0112] In an optional implementation, Fig.11 A cell undervoltage detection circuit diagram provided in this application, see Fig.11 , a cell undervoltage detection circuit provided in an embodiment of the present application includes a capacitor, multiple resistors, and multiple reverse diodes. Among them, VCC_F7V0_1 is the power supply voltage provided by the power supply, DCDC1_V+ refers to the real-time voltage of each single cell, and the controller in the battery management system determines whether there is an undervoltage condition in the single cell to be balanced based on the cell undervoltage detection circuit, and outputs an undervoltage signal LV_OUT.

[0113] In an optional implementation, Fig.12 For a cell over-voltage and under-voltage balancing circuit diagram provided in this application, see Fig.12 The controller in the battery management system compares the matching degree of the overvoltage signal OV_OUT with the balancing instruction issued by the host computer through the NAND gate, and generates an overvoltage charging protection signal corresponding to the single cell to be balanced; the controller in the battery management system compares the matching degree of the undervoltage signal LV_OUT with the balancing instruction issued by the host computer through the NAND gate, and generates an undervoltage discharge protection signal corresponding to the single cell to be balanced; the controller in the battery management system determines the overvoltage charging protection signal or undervoltage discharge protection signal corresponding to the single cell to be balanced through the NAND gate, and generates the balancing protection signal OUT_EN corresponding to the single cell to be balanced based on the charge and discharge protection signal corresponding to the single cell to be balanced, and cuts off the power supply of the balancing module through the balancing protection signal to control the balancing module to stop running.

[0114] In an optional implementation, Fig.13 A schematic diagram of the structure of a vehicle provided for this application, see Fig.13 A vehicle 13 provided in an embodiment of the present application includes the above-mentioned battery management system 10. The vehicle 13 executes the method provided in the above-mentioned embodiment through the battery management unit in the battery management system 10. The implementation principle and technical effect are similar and will not be repeated here.

[0115] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0116] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for balancing overvoltage and undervoltage of a battery cell, characterized in that: The method is applied to a battery management unit in a battery management system, the battery management system includes: a cluster management unit and a battery management unit, the battery management unit includes: a controller, a balancing module and a balancing module power supply, the battery management unit manages voltage sampling and balancing of each battery group composed of multiple single cells, and the method includes: Receive the balancing instruction sent by the host computer, and collect the voltage of each single cell in each battery pack in real time, the balancing instruction includes: the identification of the single cell to be balanced, the charging balancing instruction or the discharging balancing instruction; Generate a voltage detection signal corresponding to the single cell to be balanced according to the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced and a preset reference voltage, wherein the voltage detection signal includes: an overvoltage signal or an undervoltage signal; Generate a charge and discharge protection signal corresponding to the single cell to be balanced according to the equalization instruction and the voltage detection signal, wherein the charge and discharge protection signal includes: an overvoltage charge protection signal or an undervoltage discharge protection signal; According to the charge and discharge protection signal corresponding to the single battery cell to be balanced, a balancing protection signal corresponding to the single battery cell to be balanced is generated, and the power supply of the balancing module is cut off through the balancing protection signal to control the balancing module to stop running.

2. The method for balancing overvoltage and undervoltage of battery cells according to claim 1, characterized in that: The step of generating a voltage detection signal corresponding to the single cell to be balanced according to the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced and a preset reference voltage includes: Determining an overvoltage signal corresponding to the single cell to be balanced according to a comparison result of the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced and a maximum value of preset reference voltages; According to the comparison result between the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced and the minimum value of the preset reference voltage, the undervoltage signal corresponding to the single cell to be balanced is determined.

3. The method for balancing overvoltage and undervoltage of battery cells according to claim 2, characterized in that: The step of determining the overvoltage signal corresponding to the single cell to be balanced according to the comparison result between the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced and the maximum value of the preset reference voltages includes: If the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced is greater than the maximum value of the preset reference voltage, the overvoltage signal corresponding to the single cell to be balanced is at a low level; If the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced is less than or equal to the maximum value of the preset reference voltages, the overvoltage signal corresponding to the single cell to be balanced is at a high level.

4. The method for balancing overvoltage and undervoltage of battery cells according to claim 2, characterized in that: The step of determining the undervoltage signal corresponding to the single cell to be balanced according to the comparison result between the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced and the minimum value of the preset reference voltage includes: If the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced is less than the minimum value of the preset reference voltage, the undervoltage signal corresponding to the balanced single cell is at a high level; If the voltage of the single cell to be balanced indicated by the identifier of the single cell to be balanced is greater than or equal to the minimum value of the preset reference voltage, the undervoltage signal corresponding to the balanced single cell is at a low level.

5. The method for balancing overvoltage and undervoltage of battery cells according to claim 1, characterized in that: The step of generating a charge and discharge protection signal corresponding to the single cell to be balanced according to the equalization instruction and the voltage detection signal comprises: If the balancing instruction is a charging balancing instruction, and the voltage detection signal corresponding to the single battery cell to be balanced is an overvoltage signal, then the charge and discharge protection signal corresponding to the single battery cell to be balanced is an overvoltage charging protection signal; If the balancing instruction is a discharge balancing instruction, and the voltage detection signal corresponding to the balanced single battery cell is an undervoltage signal, then the charge and discharge protection signal corresponding to the to-be-balanced single battery cell is an undervoltage discharge protection signal.

6. The method for balancing overvoltage and undervoltage of battery cells according to claim 5, characterized in that: The charge and discharge protection signal corresponding to the single battery cell to be balanced is an overvoltage charge protection signal, including: If the overvoltage signal corresponding to the single cell to be balanced is at a low level, and the received balancing instruction is a charging balancing instruction, then the overvoltage charging protection signal corresponding to the single cell to be balanced is at a low level; If the overvoltage signal corresponding to the single battery cell to be balanced is at a high level, and the received balancing instruction is a charging balancing instruction, then the overvoltage charging protection signal corresponding to the single battery cell to be balanced is at a high level.

7. The method for balancing overvoltage and undervoltage of battery cells according to claim 5, characterized in that: The charge and discharge protection signal corresponding to the single battery cell to be balanced is an undervoltage discharge protection signal, including: If the undervoltage signal corresponding to the single cell to be balanced is at a high level, and the received balancing instruction is a discharge balancing instruction, the undervoltage discharge protection signal corresponding to the single cell to be balanced is at a low level; If the undervoltage signal corresponding to the single cell to be balanced is at a low level, and the received balancing instruction is a discharge balancing instruction, the undervoltage discharge protection signal corresponding to the single cell to be balanced is at a high level.

8. The method for balancing overvoltage and undervoltage of battery cells according to any one of claims 1 to 7, characterized in that: The step of generating a balancing protection signal corresponding to the single cell to be balanced according to the charge and discharge protection signal corresponding to the single cell to be balanced, and cutting off the power supply of the balancing module through the balancing protection signal to control the balancing module to stop running includes: If the overvoltage charging protection signal corresponding to the single cell to be balanced is at a low level or the undervoltage discharging protection signal corresponding to the single cell to be balanced is at a low level, a balancing protection signal corresponding to the single cell to be balanced is generated, and the power supply of the balancing module is cut off through the balancing protection signal to control the balancing module to stop running.

9. A battery management system, characterized in that: The battery management system comprises: a cluster management unit and a battery management unit, wherein the battery management unit comprises: a controller, a balancing module and a balancing module power supply, and the battery management unit manages the voltage sampling and balancing of each battery group composed of a plurality of single cells; The battery management unit in the battery management system is used to execute the steps of the method for balancing overvoltage and undervoltage of battery cells as described in any one of claims 1 to 8.

10. A vehicle, characterized in that: The battery management system according to claim 9 is deployed in the vehicle.

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